Question 30E3

Statement B is false because GPIRB (GPS-enabled EPIRB) signals provide significantly *more* precise location data than Doppler frequency measurements. A GPIRB integrates a GPS receiver, allowing it to transmit its exact GPS coordinates (typically accurate to within meters) directly to the COSPAS-SARSAT system. In contrast, the Doppler frequency measurement method relies on detecting frequency shifts as a satellite passes over the beacon. While effective for initial localization, this method provides a less precise location (typically within a few kilometers) compared to direct GPS data. Statements A, C, and D are all true: A) 406 MHz EPIRBs are indeed used as alerting devices in distress situations. C) The Doppler frequency measurement concept is a fundamental method used by COSPAS-SARSAT satellites to determine the location of EPIRBs that do not transmit GPS data. D) Low-Earth Orbit (LEO) satellites with polar orbits detect 406 MHz EPIRB beacons and relay this information to ground stations called Local User Terminals (LUTs).